EHRA Clinical Consensus Statement on Conduction System Pacing Implantation (2023)

Authors, Journal, Affiliations, Type, DOI

• Authors: Haran Burri, Marek Jastrzebski, Óscar Cano, Karol Čurila, Jan de Pooter, Weijian Huang, Carsten Israel, Jacqueline Joza, Jorge Romero, Kevin Vernooy, Pugazhendhi Vijayaraman, Zachary Whinnett, Francesco Zanon
• Journal: Europace (2023) 25, 1208–1236
• Affiliations: Multi-institutional; lead author from University Hospital of Geneva, Switzerland
• Type: EHRA Clinical Consensus Statement; endorsed by APHRS, CHRS, LAHRS; consensus reached by ≥80% agreement among contributing authors
• DOI: https://doi.org/10.1093/europace/euad043

Overview

Conduction system pacing (CSP) delivers pacing stimuli directly to the His–Purkinje conduction axis, providing more physiological ventricular activation than conventional right ventricular pacing. This consensus statement standardizes implantation technique, nomenclature, and capture confirmation criteria for both His bundle pacing (HBP) and left bundle branch area pacing (LBBAP), drawing on registry data (including MELOS, n=2533) and expert consensus with ≥80% agreement. The document addresses indications, procedural technique, complication recognition, device configuration, and follow-up, while acknowledging that long-term randomized trial data are still maturing.

Keywords

Conduction system pacing • His bundle pacing • Left bundle branch area pacing • Device implantation

Key Takeaways

Definitions and Nomenclature

Conduction System Pacing (CSP)

• CSP = direct activation of the conduction system by the pacing stimulus — at the His bundle, its major branches, or distal Purkinje fibres
• Capture level is determined by: (1) anatomical lead position on fluoroscopy, (2) paced QRS morphology, (3) potential-to-QRS interval

His Bundle Pacing (HBP)

• Lead near tricuspid valve summit; His potential-to-QRS interval ≥35 ms
• Selective (s-HBP): isoelectric interval in all 12 leads after stimulus; latency = HV interval
• Non-selective (ns-HBP): pseudo-delta wave present; immediate QRS onset after stimulus
• ns-HBP preferred: safer (back-up ventricular capture), better sensing; LV synchrony equivalent to s-HBP

Left Bundle Branch Pacing (LBBP)

• Lead deep in interventricular septum ~1–2 cm from His; LBB potential-to-QRS 25–34 ms; normal QRS axis
• In MELOS registry: only 9% of LBBAP cohort had confirmed LBBP

Left Fascicular Pacing (LFP)

• Capture of LBB fascicles; potential-to-QRS <25 ms; often abnormal QRS axis
• Sub-types: LAFP (leads II/III positive), LSFP (II positive/iso, III iso/negative), LPFP (II/III negative)
• Most common LBBAP type in MELOS: 69.5% (LAFP 17.2%, LSFP 27.5%, LPFP 24.8%)

Left Ventricular Septal Pacing (LVSP)

• Terminal R in V1; deep septal position; absence of conduction system capture criteria
• 21.5% of MELOS patients had LVSP

Left Bundle Branch Area Pacing (LBBAP)

• Umbrella term for LBBP + LFP + LVSP; used when differentiation is impossible/uncertain
• Requires terminal R-wave in V1 (occasionally absent)

Deep Septal Pacing (DSP)

• Lead deep in septum but not reaching LV subendocardium; no terminal R in V1, no left conduction capture features; narrower QRS than RV septal pacing

Training and Setup

• Learning curve: fluoroscopy duration flattens after 30–50 cases (HBP) and 110 cases (LBBP)
• Mandatory: 12-lead ECG + EP recording system with simultaneous endocardial signals
• Display both filtered (30–500 Hz) and unfiltered (0.5–500 Hz) channels; unfiltered essential for current of injury (COI) monitoring
• Sweep speed: 50–100 mm/s for distinguishing conduction potentials; V1 and V6 colour-coded in real time

HBP Implantation Technique

• Map His bundle in 20–30° RAO view; target near-field sharp His signal, absent/small atrial, larger ventricular EGM
• Pace mapping at 5 V@1 ms can locate His when no EGM visible (useful in AV block)
• Lead fixation: counter-clockwise rotation with forward force; torque build-up (not rotation count) indicates penetration
• COI of His potential + negative deflection of His potential = adequate tissue contact; absent COI → repeat rotation
• In AF: avoid large atrial EGM site (>0.5 mV); risk of threshold rise if AVJ ablation performed
• Confirm His capture: transitions in QRS morphology during threshold testing; difference in pacing-stimulus-to-V6RWPT vs His-potential-to-V6RWPT <12 ms (accuracy 96.7%)
• Optimal HBP threshold: ≤1.5 V/0.5 ms (acceptable up to 2.0–2.5 V@0.5 ms in HF/CRT)
• Bipolar sensing: ideally >2.0 mV; check for atrial/His oversensing (fatal in complete heart block)
• Back-up RV lead indications: pacemaker dependency, high-grade AVB, infra-nodal block, high threshold, planned AVJ ablation

LBBAP Implantation Technique

Localising the insertion site

• Use His bundle or tricuspid valve summit as anatomical marker in RAO 20–30°
• Advance sheath ~15–20 mm towards RV apex; counter-clockwise torque to reach RV basal-to-mid septum
• Initial site: 'W' pattern with nadir notch in V1; discordant QRS in leads II/III preferred
• Target sector (Liu et al.): 15–35 mm from tricuspid annulus summit, −10° to 30° angle in RAO 30°
• Lead position >16–19 mm from tricuspid annulus associated with less TR

Penetrating the interventricular septum

• Lead orientation: 10–40° (usually 20–30°) superior to horizontal in LAO 30–40° view
• 'Screwdriver effect' (smooth progression) = desired; 'entanglement' = abandon and reposition; 'drill effect' = risk of dislodgement, change position or increase push
• Five methods to monitor lead depth:
  1. Continuous fluoroscopy (LAO 30–40°) — subtle progression only
  2. Unipolar paced QRS: narrowing, R-wave in V1, V6RWPT shortening (target <80 ms)
  3. Fixation (template) beats: QR/qR/rSR' in V1 = 96.5% sensitivity, 97.4% specificity for LBB area
  4. Unipolar pacing impedance: rises then falls; <500 Ω or drop >200 Ω → caution
  5. Myocardial COI: rises to 20–35 mV intra-septally, falls to ~10–12 mV at LV subendocardium; <3–5 mV → perforation suspected

Confirming LBB capture

• Gold standard: QRS transition on threshold test (ns-LBBP → s-LBBP or LVSP)
• V6RWPT criteria:
  • <74 ms: 100% specific for LBB capture in narrow QRS/isolated RBBB
  • <80 ms: 100% specific in LBBB/IVCD/wide escape
• V6–V1 inter-peak interval: >44 ms = 100% specific; >33 ms = likely LBB capture
• Physiology-based ECG: LBB potential-to-V6RWPT = stimulus-to-V6RWPT (±10 ms); sensitivity 88.2%, specificity 95.4%
• V6RWPT sudden increase ≥15 ms at reduced output = 100% specific for loss of LBB capture
• Programmed stimulation used when threshold test non-conclusive
• Acceptable capture threshold: <1.5 V@0.5 ms (ideally <1 V@0.5 ms); bipolar sensing ideally >4 mV

Complications

HBP-specific

• Threshold rise/loss of capture: up to 17%; lead revision required in up to 11%
• Sensing issues: His/atrial oversensing, ventricular undersensing

LBBAP-specific (from MELOS and other registries)

• Septal perforation: 0–14.1%; recognized by COI drop <3–5 mV, impedance <450 Ω, ring>tip COI amplitude, loss of capture
  • Micro-perforation: may be asymptomatic; no anticoagulation required; endothelialisation likely protective
  • Overt perforation: reposition (not just withdraw)
• Right bundle branch block: 19.9% (6.3% permanent)
• Complete heart block: 9.4% acute (2.6% permanent)
• Worsening tricuspid regurgitation: 7.3–32.6% (more with proximal leads)
• Lead dislodgment: 0.3–1.5%
• Threshold rise >1 V: 0.3–1.8%
• Loss of LBB capture: 0.3–11.5%
• Troponin rise >3× normal: 49.4% (less than other EP procedures, higher than standard RV pacing)
• Coronary artery fistula: 1.4–2.0%

Device Configuration

• No dedicated CSP generator exists; use standard PM/ICD/CRT generators adapted for CSP
• Configurations determined by: anti-brady vs CRT indication; sinus rhythm vs permanent AF; need for back-up ventricular lead
• Key scenarios: (1) CSP anti-brady pacing, (2) CSP-CRT, (3) HOT-CRT (His-optimized) or LOT-CRT (LBB-optimized)
• With HBP as CSP lead: vigilance for atrial/His oversensing if connected to RV port

HBP vs LBBAP Comparison (Table 5)

Follow-up

• HBP: in-person every 6 months (ESC 2021 recommendation) due to late threshold rises
• LBBAP: more spaced follow-up acceptable if thresholds reliably measured by device
• Mandatory: paced 12-lead ECG at every in-person visit
• Check for: V6RWPT, correction of BBB, anodal capture effect on QRS width

Future Perspectives

• New dedicated leads and delivery systems in development
• Leadless pacemakers designed for CSP under development
• AI-assisted capture detection being explored
• Long-term extraction safety of LBBAP lead needs study
• Large RCTs with long-term follow-up needed before CSP becomes universal first-line pacing

Limitations of the Document

• Consensus document based on observational registry data (no large RCTs)
• Learning curve bias in early registries (MELOS); complication rates likely improving
• No dedicated CSP hardware; all recommendations adapted from non-CSP devices
• Whether conduction system capture (vs LVSP) is required for clinical benefit remains uncertain
• Long-term lead extraction data for LBBAP lead (3830 in LBB position) very limited

Key Concepts Mentioned

• concepts/Conduction-System-Pacing — core topic of this document
• concepts/His-Bundle-Pacing — detailed technique and capture criteria
• concepts/Left-Bundle-Branch-Area-Pacing — detailed technique, sub-types, and capture criteria

Key Entities Mentioned

• entities/Heart-Failure — CSP used as CRT alternative; HOT-CRT and LOT-CRT configurations
• entities/Atrial-Fibrillation — LBBAP preferred over HBP when AVJ ablation planned; HBP threshold rise risk with AVJ ablation

Wiki Pages Updated

• wiki/sources/csp-ehra-2023.md (created)
• wiki/concepts/Conduction-System-Pacing.md (created)
• wiki/concepts/His-Bundle-Pacing.md (created)
• wiki/concepts/Left-Bundle-Branch-Area-Pacing.md (created)
• wiki/wikiindex.md (updated)
• wiki/sourceindex.md (updated)